TESTING/EIG/csyl01.f(3)

NAME
TESTING/EIG/csyl01.f

SYNOPSIS

  Functions/Subroutines
subroutine csyl01 (thresh, nfail, rmax, ninfo, knt)
CSYL01

Function/Subroutine Documentation

  subroutine csyl01 (real thresh, integer, dimension( 3 ) nfail, real, dimension( 2 ) rmax, integer, dimension( 2 ) ninfo, integer knt)

CSYL01

Purpose:

    !>
    !> CSYL01 tests CTRSYL and CTRSYL3, routines for solving the Sylvester matrix
    !> equation
    !>
    !>    op(A)*X + ISGN*X*op(B) = scale*C,
    !>
    !> where op(A) and op(B) are both upper triangular form, op() represents an
    !> optional conjugate transpose, and ISGN can be -1 or +1. Scale is an output
    !> less than or equal to 1, chosen to avoid overflow in X.
    !>
    !> The test code verifies that the following residual does not exceed
    !> the provided threshold:
    !>
    !>    norm(op(A)*X + ISGN*X*op(B) - scale*C) /
    !>        (EPS*max(norm(A),norm(B))*norm(X))
    !>
    !> This routine complements CGET35 by testing with larger,
    !> random matrices, of which some require rescaling of X to avoid overflow.
    !>
    !>

Parameters
    THRESH

    !>          THRESH is REAL
    !>          A test will count as  if the residual, computed as
    !>          described above, exceeds THRESH.
    !>

    NFAIL

    !>          NFAIL is INTEGER array, dimension (3)
    !>          NFAIL(1) = No. of times residual CTRSYL exceeds threshold THRESH
    !>          NFAIL(2) = No. of times residual CTRSYL3 exceeds threshold THRESH
    !>          NFAIL(3) = No. of times CTRSYL3 and CTRSYL deviate
    !>

    RMAX

    !>          RMAX is DOUBLE PRECISION array, dimension (2)
    !>          RMAX(1) = Value of the largest test ratio of CTRSYL
    !>          RMAX(2) = Value of the largest test ratio of CTRSYL3
    !>

    NINFO

    !>          NINFO is INTEGER array, dimension (2)
    !>          NINFO(1) = No. of times CTRSYL where INFO is nonzero
    !>          NINFO(2) = No. of times CTRSYL3 where INFO is nonzero
    !>

    KNT

    !>          KNT is INTEGER
    !>          Total number of examples tested.
    !>

Definition at line 88 of file csyl01.f.

Author

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